Electric heating unit for tanks



K. R. KUENNE ELECTRIC HEATING UNIT FOR TANKS 2 Sheets-Sheet 1 Filed Oct. 21, 1947 INVENTOR. KU/VO R. KUEN/VE.

Oct. v18, 1949. K. R. KUENNE 2,484,893

ELECTRIC HEATING UNIT FOR mxxs Filed Oct. 21, 1947 2 Sheets-Sheet 2 I I I l I .'l i ma f9 IN V EN TOR Patented Oct. 18, 1949 2,484,893 ELECTRIC HEATING UNIT FOR TANKS Kuno Robert Kuenne; Oconomowoc, Wis assignor to A. J.

Lindemann & Hoverson Company, Milwaukee, Wis., a corporation of Wisconsin Application October 21, 1947, Serial No. 781,207

10 Claims. 1.

The improvements relate to electric heating devices ior hot water tanks, and more particularly to devices adapted to beapplied to the exterior of such tanks-usually to upper and lower parts thereof-in the form of a band or girdle surrounding it and insulated from the outer atmosphere by the jacket of non-heat-conducting material with which such tanks are usually provided. They may, however, be used for any purpose to which they may be adaptable.

The primary objects of the improvements are to produce an electric heater of the kind indicated of relatively simple, strong, eflicient and durable construction in which all the essential parts are assembled to form a single unitary structure or unit and one which can be quickly and easily applied between the tank and its heat insulating jacket and without any modification of that tank and jacket or the use of any additional structure or any intervening devices of any kind. Other objects and purposes and their advantages will appear from the following specification and the accompanying drawings.

Heretofore it appears to have been the most usual practice to first provide and apply to the shell of the tank a fixed and permanently secured metallic sheath or channel-sometimes called a tunnel-to receive and support in position the electric heating unit and protect it, as well as the outer jacket of the tank, against injury in use and when the said unit is removed for repairs or replacement. This not only adds greatly to the cost of construction in labor and materials but requires r interference provisions between the heating unit, the tunnel and the tank, and is attended by other disadvantages, well recognized in the art. Yet no satisfactory construction in which this fixed outer sheath r tunnel has been dispensed with appears to have been produced,v althoughv the need for it has long been obvious and many unsatisfactory efforts by those working in the art have been made to supply that need. The primary object of the present improvements is to meet this long felt need and overcome these: well recognized disadvantages, and at the same time to provide a more eflicient and less costly heating unit for the purpose stated.

In the said drawings, Fig. 1 is a horizontal section of an electric heating'unitpositioned on a tank, showing an exemplary embodiment of the present invention on line ll of Fig. 4;

Fig. 2 is an inside view ofan end portionof the unit before its application" to-a'tank andin' the ather complicated insulation and non Fig. 3 is an enlarged vertical section substantially on the line 3-3 of Fig. 1;

Fig. 4 is a diagrammatic side view of a tank with upper and lower units applied thereto.

In the drawings, the connections between the resistor and the. source of electric current and the thermostat for controlling that current by the desired temperatures have not been shown in detail, as these are old, common and well known in the art. The cylindricalwallor shell of the tank is shown at I, its inlet pipe at Zand outlet 3 and its upper cap or cover at 4, while the jacket or layer of heat-insulating material is shown at 5 and its outside sheath of light-gauge sheet metal at 6. The thermostat is indicated at 1 and the connection between the electric resistance heating member andthe source of electric current at 8. Thesemay all be'of usual and ordinary construction and material and need no further illustration or description. A slight space or clearance between the heat-insulating material and the sides of the heating units isshown at 9.

The elastic heating unit comprises essentially the resistor l0, its supporting insulators II and the flexible band l2 with its contractible flange l3 and feet 14 in which the resistor is mounted by means of the insulators.

The band I! is preferably a strip of light gauge sheet metal, such as aluminum or an aluminum alloy, and ishighly flexible and resilient and also highly reflective. Its outer surface is smooth and unbroken sothat it will slip through the insulating material with very little friction and will not catch on any irregularities thereof. The flanges [3 are stamped from the same elongated sheet of metal as the band and extend inwardly there- IrOm at both edges substantially from end to end at an angle-of between and to the plane of the band. They are also highly flexible and are provided with numerous spaced V-shaped notches or slitsl3" flaring inwardly toward the tank shell, the total maximum width of these notches being about equal to the excess of the circumference of the outer edges of the flanges and band and that" of the shell when wrapped around the "latter, so'that when the heatin unit is bent around the shell'to' form a ring or girdle thereon the-'said'notcheswill close up the space insideand also give the flanges a substantially continuous, smooth surface to be presented to the insulating material through which they pass.

The flanges 13 are provided along their inner edges'with root flanges l4- turned horizontally and then folded beckon themselves as shown at I5 and'throughwhlch the notches l3 extend, so that when the unit is applied to the tank shell these notches also will close up approximately and present substantially a smooth continuous surface of the feet to the insulating material jacket and the surface of the tank shell. The folded over portions [5 form sheaths for the reception of flexible metal straps Hi running through them around the unit and provided with end flanges I! turned outwardly and apertured to receive tension screw bolts l8 whereby the unit is secured on and tightly clamped to the shell after being applied thereto. The end flanges I! also prevent the straps from pulling through the sheaths of the foot flanges when the unit is being removed and replaced, in the manner hereinafter described.

The insulator holders II are positioned in spaced apertures l3" of the opposed flanges I 3 located between the notches 13', have enlarged outer bases l9, hook-form inwardly extending portions 20 and recesses 2| in their bases engaging one of the edges of the apertures, so that they may be inserted through said apertures from either side of flange l3 and will maintain their position therein. They are preferably arranged opposite one another, as are also their apertures, but may be in different relation. The resistor I is strung on the hook portions 20 of the insulator holders running in zig-zag fashion and out of contact with all other parts around the heating unit. It is preferably a spirally twisted wire and resilient lengthwise as well as laterally and is held in the holders .by tension. It also tends to hold the said holders in inwardly extending position in the flange l3 and away from said flange and its band l2.

In use the unit is applied to the hot water tank by wrapping it around the outside thereof and securing the end flanges ll of the straps l6, and drawing the straps tight by means of the bolts 18. This presses the feet l4 against the outer surface of the tank, binds the unit thereon with the notches l3 substantially closed, so that the flanges and their feet with the band l2 and the wall of the tank form a substantially closed housing and supporting frame for the resistor and the insulators secured therein, except for a small space between the ends of the unit spanned by the bolts I8, which may be closed by insulating material before the space is closed by the cover 22 mounted over an opening in the outer metal jacket which coincidesv with the space. The outer layer of insulating material 5 is then applied, preferably after the resistor or resistors have been connected with the electric service wiringthrough a thermostat 'or thermostats. The outer light metal wrapping or sheathing 6 is then applied to enclose the heat insulating jacket 5 in the usual manner. If the insulating jacket 5 is of cohesive material it is advisable to first form an annular groove therein slightly larger in cross section than the heating unit and approximating its form so that there will be no fixed engagement between these parts. It will be noted, however, that as the band and its feet are substantially smooth and unbroken and the portions IQ of the insulators which project slightly beyond the flanges l3 are rounded or beveled there will be no engagement between these parts and the jacket,

If it becomes necessary to remove the heating unit from the tank, as for repair or replacement, the bolts I8 are removed and the ends of a plain wire loop secured to the bolt apertures in the turned end flanges I] of the strap on one side of the terminal aperture. The unit is then drawn out by pulling on the opposite end of the straps and thus drawing one end of the loop of the plain wire through the annular space between the shell of the tank and its jacket previously occupied by the unit and leaving the other end of the loop projecting out through the end space. Then when the unit is replaced it is only necessary to secure the ends of the straps to the loose ends of the wire which were previously secured thereto and draw the unit back through the annular space left by the removal. This is done by pulling on the opposite and closed end of the wire loop.

Before restoring the repaired heating unit or a new unit to the tank a coating of semisolid lubricant should be applied to the feet which contact the surface of the tank to reduce the friction between them. It will be found that the unit will slip easily over and around the tank outer wall and through the insulating material, since there are no projecting parts to catch in such material or produce retarding friction, and nothing in the nature of a tunnel or lining is needed. The portions of the insulating holders on the outside of the flange l3 may, however, be countersunk therein if desired.

After the heating unit has been positioned on the tank and properly connected the terminal space is preferably filled with loose heat insulating material 23, such as fibreglass, before applying the cover 22, so as to prevent urmecessary loss of heat at that point.

Various modifications of the details of the exemplary embodiment herein described and shown may be made without departing from the scope and purport of the invention.

What I claim is:

1. In a device of the character described adapted to be positioned between the shell of a hot water tank and a jacket of insulating material surrounding said shell, a girdle-like heating unit in contact with said shell comprising a substantially flat flexible metal band of substantially continuous and unbroken form and of length approximately equal to the horizontal circumference of the shell and adapted to encompass the exterior of the same in spaced relation thereto, integral flanges projecting inwardly along the side edges of said band and adapted to contact said shell and space the band from the shell, said flanges having inwardly flaring notches runsize and form to permit said flanges when bent around the shell to contract progressively inwardly and assume a substantially closed annular form, a series of spaced insulating holders mounted in said flange and extending away from said flanges and band, an electric resistor in communication with a source of electric current strung 0n and positioned between said insulating holders and spanning the space between the holders on each flange and out of contact with the said band and its flanges and means for connecting and tensioning said band and flange on the shell and securing them thereon, the said elements above recited forming a unitary electric resistance heating member in direct contact with the shell and its insulating jacket but removable therefrom as a unit.

2. In a device of the character described adapted to be positioned between the shell of a hot water tank and a jacket of insulating material surrounding said shell, a girdle-like heating unit in contact with said shell comprising a substantially flat flexible metal band of substantially continuous and v unbroken form and. of length approximately equal: tozthe horizontal circumference of the shell andiadapted' to. encompass the exterior of the-same'in: spaced relation thereto, integral flanges projectingv inwardly along both side edges. of. said band. having. laterally turned foot portions andadapted to contact said shell and space the band; from the; shell, said flanges and their said feet having a series of inwardly flaring notches running through them' of a size and form to permit. said flanges when bent around the shell tocontract progressively inwardly and assume a. substantially closed. annular form, a series of spaced insulating holders mounted in said flange; and. extending away from said flanges and band, an electric resistor in communication with a source of electric. current strung on and positioned between said insulating holders and spanning the space between the holders on each flange. and. out of contact with the said band and its flanges. and means for connecting and tensioning said band and flange on the shell and securing them thereon, the said elements above recited forming. a unitary electric resistance heating member in direct contact with the shell and its insulating, jacket but removable therefrom as a unit.

3. In a device of the. character described adapted to be positioned between the shell of a hot water tank anda jacket of, insulating material surrounding said shell, a girdle-like heating unit in contact with said'shell' comprising a substantially flat flexible metal band of substantially continuous and unbroken form and of length approximately equal to the horizontal circumference of the, shell and adaptedto encompass the exterior of the same in spaced relation thereto, integral flanges projecting inwardly along the side edges of said band and adapted to contact said shell and space the band from a the shell, said flanges; having inwardly flaring notches running through them of a size and form to permit said flanges when bent around: the shell to contract progressively inwardly and assume a substantially closed annular" form, said feet being folded over to form a continuous sheaf and a strap-like metallic band in said sheaf extending through the same throughout its length, a series of spaced insulating holders mounted in said flange and extending away from said flanges and band, an electric resistor in communication with a source of electric current strung on and positioned between said insulating holders and spanning the space betweenthe holders on each flange and out of contact with the said band and its flanges and means for-connecting andtensioning said band and flange on the shell andsecurin them thereon, the said elements above recited forming a unitaryelectric resistance heating member in direct contactwith the shell and its insulating jacket but removable therefrom as a unit.

4.. In a device. of the character described adapted to be positioned between; the shell of; a ,hot water tank and a jacket of insulating material surrounding said shell, a girdl'e-likeheating unit in contact with said shell. comprising a substantially flat flexible metalbandzofsubstantiallyi'continuous and unbroken form. and? of length; ap-

proximately equal to the horizontal circumference of the shell and adapted to encompass the. exterior of the same in spaced relation thereto, integral flanges projecting inwardly along the side edges of said band and adapted to contact said shell and space the band from the shell, said flange; having inwardly flaring. notches running through them of a size and-form to permit said flanges when bent aroundtheshell. to contract progressively inwardly: and. assume a. substantially closed annular form, a. series. of spaced in?- sulating holders in. the form of hooks mounted in said flange. and extending away from said flanges and band, said flange being provided with a.series of apertures. through which said hooks extend inwardly, anelectricv resistor in communication with a source of. electric. current: strung on and positioned between said insulating holders and spanning the space between the holders on each flange. and outofcontact with the said band and. its flanges and means for connecting. and tensioning said band and flange. onthe shell and securing them thereon, the said elements above recited forming a unitary electric resistance heating member in direct contact withthe shell and its insulating jacket but removable therefrom as a unit.

5. In a device of the character described adapt.- ed to be positioned between. the shell of. a. hot water tank and a jacket of insulating material surrounding said shell,. a girdle-like heating unit in contact with said shell comprising a substane tially flat flexible metal band; of substantially continuous and unbroken formand of: length approximately equal to the horizontal circumference of the shell and adapted to. encompass the exterior of the same in spacedrelationthereto, integral flanges projecting inwardly alongthe side edges of. saidv band and adapted to contact said shell and space the bandifromthe shell,. said flanges having inwardly flaring notches running through them of a size and form to permit said flanges when bent around the shell. to contract progressively inwardly and assume. a substantial.- ly closed annular form, a series of spaced insulating holders mounted in said flange andextend'a ing away from said flanges. and band, and. said holders being provided with outer bases larger thansaid apertures, an electric resistor in com.- munication with a source of electric current strung on and positioned between said insulating holders and spanning. the space between the hold"- ers on each flange and out of contact withthe .said band and its flanges and means for connecting and tensioning said band and flange on the shell and securing them thereomthe said elements above recited forming a unitary electric resistance heating member in direct contact with the shell and its insulating. jacket but removable therefrom asa unit.

6. In a device of the character described adapted to be positioned between the shell of a. hot

water tank and a jacket of insulating material surrounding said shell, a. girdle-like heating unit in contact with said shell comprising asubstanside edges of said. band and adapted to contact said shell and space the. band from the. shell,

said flanges having inwardly flaring, notches. rune ..ning through them. of a size and form. to: permit said flanges when bent around the. shell to. contract progressively inwardly and assume a substantially closed annular form, a series of spaced insulating holders mounted in said flange and extending away from said flanges and band. an electric resistor in communication with a source of electric current strung on and positioned between said insulating holders, said resistor being spiral in form and lengthwise stretchable and spanning the space between the holders on each flange and out of contact with the said band and its flanges and means for connecting and tensioning said band and flange on the shell and securing them thereon, the said elements above recited forming a unitary electric resistance heating member in direct contact with the shell and its insulating jacket but removable therefrom as a unit.

'7. In a device of the character described adapted to be positioned between the shell of a hot water tank and a jacket of insulating material surrounding said shell, a girdle-like heating unit in contact with said shell comprising a substantially flat flexible band of substantially continuous and unbroken form and of length approximately equal to the horizontal circumference of the shell and adapted to encompass the exterior of the same in spaced relation thereto, integral flanges projecting inwardly along the side edges of said band and adapted to contact said shell and space the band from the shell, said flanges having inwardly flaring notches running through them of a size and form to permit said flanges when bent around the shell to contract progressively inwardly and assume a substantially closed annular form, a series of spaced insulating holders mounted in said flange and extending away from said flanges and band, an electric resistor in communication with a source of electric current strung on and positioned between said insulating holders and spanning the space between the holders on each flange and out of contact with the said band and its flanges and means for connecting and tensioning said band and flange on the shell and securing them thereon comprising bent inwardly extending vertical flanges at the ends of said band flanges and a contractible connecting member engaging said vertical flanges, the said elements above recited forming a unitary electric resistance heating member in direct contact with the shell and its insulating jacket but removable therefrom as a unit.

8. In a device of the character described adapted to be positioned between the shell of a hot water tank and a jacket of insulating material surrounding said shell, a girdle-like heating unit in contact with said shell comprising a substantially flat flexible metal band of substantially continuous and unbroken form and of length approximately equal to the horizontal circumference of the shell and adapted to encompass the exterior of the same in spaced relation thereto, integral flanges projecting inwardly along the side edges of said band and adapted to contact said shell and space the band from the shell, said flanges having inwardly flaring notches running through them of a size and form to permit said flanges when bent around the shell to contract progressively inwardly and assume a substantially closed annular form, a series of spaced insulating holders mounted in said flange and extending away from said flanges and band, an electric resistor in communication with a source of electric current strung on and positioned between said insulating holders and spanning the space between the holders on each flange and out of contact with the said band and its flanges and means for connecting and tensioning said band and flange on the shell and securing them thereon, the said elements above recited forming a unitary electric resistance heating member in direct contact with the shell and partly with its insulating jacket but removable therefrom and insertible between them as a unit by sliding said unit through an annular clear space between the said shell and insulating jacket.

9. In a device of the character described, a girdle-like heating unit adapted to be passed around and positioned in close contact with the shell of a hot water boiler, said heating unit comprising a flat imperforate metal band, integral flanges extending inwardly from said band throughout its length and integral feet flanges extending laterally therefrom and in contact with said shell, and a resistor extending through said band and its flanges from side to side and from end to end mounted therein and united therewith but in spaced relation thereto and to said metal band, said flanges having numerous outwardly flaring slits therein and extending laterally therethrough, the total width of the (extremities of said slits being approximately equal to the difference in length between the circumference of the band and the circumference of the foot flanges, whereby when said unit is positioned around the shell of a tank the said slits will be substantially closed and will present in effect closed up surfaces.

10. In a device of the character described, a girdle-like heating unit adapted to be passed around and positioned in close contact with the shell of a hot water boiler, said heating unit comprising a flat imperforate metal band, integral flanges extending inwardly from said band throughout its length and integral feet flanges extending laterally therefrom and in contact with said shell, and a resistor extending through said band and its flanges from side to side and from end to end mounted therein and united therewith but in spaced relation thereto and to said metal band. said flanges having numerous outwardly flaring slits therein and extending laterally therethrough, the total width of the extremities of said slits being approximately equal to the difference in length between the circumference of the band and the circumference of the foot flanges, whereby when said unit is positionedaround the shell of a tank the said slits will be substantially closed and will present in effect closed up surfaces, said unit adapted to be inserted between a tank shell and its exterior lining of insulating material and to be passed around the tank between them without the intervention of any means for preventing contact between the unit and said jacket.

KUNO ROBT KUENNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

